1. relating to or situated in the small spaces between things
Usage: medical; technical
2. occurring in the intervals between regular activities or events

1. a brief advertisement or announcement inserted between regular programming
Usage: media

Examples

• The doctor found interstitial fluid between the tissue layers.
• Interstitial lung disease affects the spaces around the air sacs.
• The museum offered interstitial activities between the main exhibits.
• Radio stations play interstitial announcements between songs.
• The interstitial spaces in the rock formation contained water.
• An interstitial ad appeared between the video segments.
• The interstitial period allowed for equipment maintenance.